1. Field of the Invention
The present invention relates to an apparatus and method for insulating beverage containers and container stock material. In particular, the present invention relates to an insulated, paper-based beverage container or stock material having improved insulation properties and a method of producing these insulated containers or stock materials.
2. Description of the Background Art
Current standard paper cup stock permits excessive heat transfer through the wall of an insulated beverage container. Accordingly, a user's hand becomes uncomfortably or sometimes even painfully hot when excessive heat transfer is permitted through the container wall. This may require the user to be inconvenienced by having to release the container due to the excessive heat of the container's contents. An analogous but opposite situation can occur with very cold beverages, where heat transfer from a user's hand is transferred rapidly to the contents of the container.
U.S. Pat. No. 4,435,344 to Ioka describes a method for producing an insulating composite paper container having a body member and a bottom member. The body member is formed of paper coated or laminated with a thermoplastic synthetic resin film. A surface of the body member is then heated to form a foamed polyethylene heat-insulating layer on either or both of inner and outer surfaces of the container's body member. The heat-insulated body member is then attached to the bottom member.
U.S. Pat. Nos. 6,030,476 and 5,840,139 to Geddes et al. describe a method for producing insulating beverage containers or cups, stock material and containers made therefrom. A stock material includes a base layer, an insulating layer formed on a portion of the base layer, and a printed pattern/mineral oil applied to the insulating layer. The insulating layer is formed from a thermoplastic synthetic resin film.
The devices and methods of the background art suffer from the following disadvantages. Other known designs sacrifice the outside printability of the cup to provide insulation or do not provide adequate insulation properties. The related art has not yet achieved insulated paper stock that is capable of effectively impeding heat transfer between the contents of the container and the exterior. In addition, adequate thermal insulation is not achieved from the related art in a manner that is cost effective.